No features would be lost compared to before, as there's still the server part running which can e.g. store configuration files or show an LT icon in the task bar. In other words, we're not limited by what Javascript can do. Privacy is as good as with the old stand-alone version, as no personal data leaves the user's computer.

What's good about this?

We'd be using the same technology for the stand-alone client and the web interface

By doing so, the interface at languagetool.org would become complete, features like rule configuration would be added

We'd be using technologies that are more widespread among developers than Swing is

It's easy to add a "remote" mode, where a different LT server is used instead of the local one (e.g. to take advantage of the ngram data which is available on languagetool.org, but usually not locally)

What's bad about this?

HTML + Javascript + CSS + server part is at least as complex as Swing

It's a lot of work

Status

There's an incomplete prototype implementation, see page attachments. The main class to start is LocalWebAppConcept.